High pH

tex_jas(8b - College Station, TX)May 3, 2008

Hi folks. Ive made a couple of posts here in recent weeks about my sad looking St. Augustine lawn. I had sent off for a soil test before finding you all, and I finally got the results back today (done at Texas A&M University).

Of most concern to me in the results is my soil's pH. While IÂve applied chemical fertilizers like ScottÂs in the past, IÂve never applied anything else (like lime for example). Somehow or other, my pH came back as 8.8.

Sulfur, iron sulfate, or aluminum sulfate seem to be the weapons of choice, but IÂm getting the impression that lowering pH this much is close to impractical. IÂve found a chart that says to drop pH by one point you need to apply sulfur at 24 lbs / 1000 sqft, and to multiply that application rate by 6 if you wanted to use quicker-acting iron or aluminum sulfate.

It sounds like I have a good chance of burning the lawn (and any microbes if I even have any!) with any of these.

Anyone been faced with a similar situation?

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Yipes! You have a problem! Fortunately you live in Texas and should be able to locate the following. Do a search for the organic product "Back to Nature Acidifier Cotton Burr Compost". Contrary to what some may post, it comes from organically raised cotton. And, from personal experience it is an excellent product which should be sold by every nursery for use on acid loving plants. Also, those gardening in heavy clay will find that it most helpful in turning clay to friable soil.

My suggestion is top dress the lawn early spring and fall with the cotton burr compost plus order in a gallon of Humic Acid on line. A little searching should help you locate a source. I suggest using Humic Acid because it will help to lower pH used over a period of time. Lots of interesting reading about it, pro and con as to effectiveness. Take it all with a grain of salt as you basically need its acidifying properties. It is applied with a hose end sprayer and I would treat the lawn once a month with this.

I can assure you that both products will not burn a lawn and with annual due diligence you should see some improvement.

    Bookmark   May 3, 2008 at 5:27PM
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The idea of 'buffering' the ph sounds like it is applicable here. If you have a good amount of OM along with the accompanying microbes your high ph is of minimal consequense to the lawn.
You could start the process of sulfer, but more heavily add compost. Over time you should see improvements. :)

    Bookmark   May 3, 2008 at 5:37PM
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tex_jas(8b - College Station, TX)

Thank you both! It at least sounds like there's some hope.

I got to thinking about something after I wrote the original message here. A couple of years ago, I was doing a "tree care" program that one of the local plant shops put together. I had forgotten about this, but in hindsight, the St. Aug around the trees where I was applying this was substantially outgrowing the rest of the lawn.

I dug up the to-do list from that and, while it had a little bit of everything in it over the course of a year, there were three pretty heavy applications of sulfur, and two of gypsum. Maybe I should have been more inquisitive a couple of years ago. :)

Maplebirch, my OM was actually pretty low too. It came back at 1.06%. I've been applying compost tea the past three weekends... There's pleny of dead grass for the little guys to break down if they're actually staying alive. :) I probably need to do as you guys say though and do an actuall compost top-dressing.

    Bookmark   May 3, 2008 at 6:52PM
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billhill(z5 MI - KBG)

Don't forget the free compost you get by mulch mowing yours and all additional leaves you can import into your lawn. Shred them well with your mulching mower and let them de-compost in place over winter.
Bill Hill

    Bookmark   May 3, 2008 at 7:59PM
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Peat moss has a nice, acidic pH (about 4.4) and would also add some organic matter if you topdress a quarter inch.

It's nothing extreme, but every little bit helps. Feed organically and the pH will buffer itself toward 7.0.

One little thing to keep in mind is that acid plus base equals salt. Shifting the pH too quickly can result in a lot of salt buildup, particularly if rainfall is limited. Portions of Texas definitely fit that bill, others don't.

    Bookmark   May 3, 2008 at 9:12PM
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tex_jas(8b - College Station, TX)

I (sort of) wish I had leaves to contend with, Bill. We're in a new neighborhood. The native tree around here is a Post Oak. If you even look at them funny, they die unfortunately, so it's pretty common to just remove them from the lot and have a do-over. Have always mulch mowed though.

I'm liking the peat idea, Morpheus. It has crossed my path a time or two when I was looking into my thatch problem a few weeks back. Is there a point in the season when it's too late to topdress?

    Bookmark   May 3, 2008 at 9:58PM
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I wouldn't try lowering the pH using sulfur. Sulfur works best worked into the soil. The problem with applying it on the surface (which is the only thing practical working with something like a lawn) is that too much of the sulfur combines with the air and goes into the atmosphere as sulfur dioxide (S02). You want it to combine with water to become sulfurous acid (H2SO3. If it's buried, there's a bacteria that digests it and turns it into sulfurous acid. Some of that happens if it's applied on the surface, but you lose a lot.

The main problem from a high pH soil is iron chlorosis. If your lawn is showing signs of chlorosis (yellowing grass blades), there's a product that is available in Texas called greensand (sometimes called glauconite) that can be applied to provide iron that is readily available to the grass. The iron in iron sulfate will not be available to the grass unless it is applied as a foliar spray, and then it will be available for a very short time and can also cause burning if it is applied at the wrong time or if too much is used.

If you plant trees, take care in choosing them to make sure you only plant trees that are adapted to high pH. It's a lot easier to try to get plants that will do well in your soil than to try to change your soil to something that will do well for the plants.

    Bookmark   May 3, 2008 at 11:16PM
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I'm liking the peat idea, Morpheus. It has crossed my path a time or two when I was looking into my thatch problem a few weeks back. Is there a point in the season when it's too late to topdress?

Nope, you can topdress in January or July. It even provides some mulching effect, so the lawn ends up requiring a little bit less water. You can topdress whenever the old stuff works its way in (about three months-ish, depending on the weather, insect activity, and so on).

The organic feedings are important, too. My pH has moved from 5.8 to 6.9 just from that.

    Bookmark   May 4, 2008 at 6:59AM
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tex_jas(8b - College Station, TX)

BP, I definitely have yellowing grass. In the April 23 folder in this LINK I had put up some close-up pics of how the grass was yellowing. The consensus of the group at that time (based on the information that I was able to provide) was that the grass was starving. I applied a "mostly" organic (that's another story in another thread!) fertilizer on Apr 24 as a result. The soil test I received yesterday did indicate that from an NPK standpoint it was low (with Nitrates being pretty much non-existant at 1 ppm).

That said, we had planted 4 Live Oaks, 1 Red Oak, 4 large Crape Murdles that are all doing fine still. I had done the "tree care" previously mentioned) though, so they may just be on the borderline.

Would iron chlorisis be represented in the soil test? My iron level was relatively close to normal... Just a little high, actually. Can iron get "locked up" from the plant's standpoint by other things at play that are causing the high pH? Or do you guys think it's the absence of nitrates?

Shoulda done this in the first post, but below is the entire soil report. Again, this was from samples taken before I put down the organic fert and 3 compost tea applications, so hopefully the little guys are starting to free up some nitrates by now.

Here's a if the image above doesn't show up.

Chemistry is not my strong point (nor is lawn care obviously!), but in trying to decipher all of this, I've read a few things that make me think the high Ca level is probably the root cause of my pH problem. Does that go along with anyone's thinking?

I homebrew beer, and proper pH is a critical part of one of the steps. I have a magic buffer simply called "5.2" that raises or lowers the pH to 5.2 in this phase. I need some magic "6.2" for my soil. :)

I haven't come across the Acidified Cotton Burr Compost around here yet (but am going to D/FW area next weekend and it seems to be pretty common up there), I have seen greensand and peat here in town though. You all make good sense, so it may come down to drawing straws. :)

    Bookmark   May 4, 2008 at 9:48AM
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Can iron get "locked up" from the plant's standpoint by other things at play that are causing the high pH? Or do you guys think it's the absence of nitrates?

Yes and yes. Iron locks at a pH of over 7 (it's locking lower than that, but it becomes severe over neutral). A lack of nitrogen would also cause yellowing in the lawn.

I didn't see your image, and the link comes back as Forbidden, so I'm not sure what you'd need.

Still, I stress organics again because of the buffering ability...

    Bookmark   May 4, 2008 at 10:24AM
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tex_jas(8b - College Station, TX)

Sorry, here's another try...


    Bookmark   May 4, 2008 at 10:39AM
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Got it. You're low on Phosphorous, Potassium, and Nitrogen. You can ignore the nitrogen as it varies wildly from place to place, day to day, and even hour by hour depending on the weather.

Your iron levels are fine, but a foliar spray of iron might be a good idea with a pH as whacked as yours is. Your grass probably can't get any out of the soil.

Synthetically, the first time would use a good balanced fertilizer (like 10-10-10). Hit it with that again in fall and test again next spring. If you want to go synthetic, that is, which doesn't seem to be the case.

Organically, any of the grains would do fine. I'd hit it with cracked corn (about 3-1-2) heavily one time, then shift to soybean meal (7-1-2) for the rest of the year, and maybe a bit of alfalfa if I could get that.

The corn meal and alfalfa will help with the P and K without overdoing the N, while the soybean helps a bit with P and K but gives plenty of N for your grass. The fungal and bacterial activity those cause will also help release micronutrients, including iron.

For corn meal, you could theoretically go to 40 lbs per thousand square feet without overdoing nitrogen. Warning, it'd smell as it decays. When that happens to me, I tend to look innocent and disavow all knowledge of anything being awry with my lawn and gardens. It fades in a week or so.

20 lbs per thousand won't stink, and you can certainly do that now and again four weeks later. If you do it that way you'll be nitrogen short (0.5 lbs per thousand), so I'd go 15 lbs per thousand and 5 lbs per thousand of soybean meal for a total of 0.80 lbs of nitrogen per thousand square feet.

I doubt it'll make much difference visibly as anything is going to help.

Yes, NPK is the wrong way to think of organics, but with a poor lawn and tapped nutrients, it's not a bad place to start.

All of them will pull the pH back into line slowly, although the pH will be much less important as your bacteria and fungi will be the sort that don't mind it. As it slowly shifts, the populations will shift too.

    Bookmark   May 4, 2008 at 11:51AM
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tex_jas(8b - College Station, TX)

Excellent, thank you very much Morpheus! I was the one in the other thread that was all proud that I applied my first organic fertilizer and then I found out that wasn't quite the case. So I did get some food in there last week. Should I let that bake a few more weeks before making another round with your suggestions?

I just came back with a truckload of peat. Safe to assume that's still a good idea? I've never had the joy of topdressing. It's going to be a lonnnng day it looks like.

Thanks again Morph & everyone else!

    Bookmark   May 4, 2008 at 12:41PM
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dchall_san_antonio(8 San Antonio)

Somehow or other, my pH came back as 8.8.

All I can say is, "Welcome to Texas!" We have cockroaches too.

I thought everyone knew that we gardened in pure limestone rubble and dust. That is what we have so all you have to do is buy plants that are adapted to the soil and lack of rain. If you are unhappy about that, then don't check your water. It has lots of dissolved calcium in it too. Of all the replies I seen here, bpgreen has done the most homework.

If you are worried about iron, the only product that works is greensand. It seems to me you already mentioned where you live on another post. Would you mind supplementing your member page with your location so we don't have to continue asking? I could probably direct you to a garden shop that carried greensand if I remembered where you were. The application rate is 40 pounds per 1,000 square feet.

Here's how this gardening on limestone soil works: First you fertilize with organic fertilizer to feed the soil microbes. Generally it is the bacteria that exude acidic goo. You may have heard of humic acid (also called humates) and fulvic acid. These are not acids in the sense of vinegar or sulfuric acid, but more like buffering agents that are slightly to the acidic side of 7.0 on the pH scale. These acids will tend to pull your soil pH toward neutral, release the bound up iron, and allow you to garden with some success.

While the acidic buffering agents work well in normal conditions, the time they let you down is when you get a rainstorm that lasts several days. When you get enough water, the rain will wash the acidic buffering agents out of the soil surface and reset your soil pH to 8.8 again. The very first thing that happens next is the iron binds up and becomes "unavailable" to your plants. You can fertilize daily from then on and you will not restore your color until the following spring. However, if you recognize the rainstorm as it happens, you can rush out and get some greensand and apply it even while it is still raining. With that one application you can forestall the entire chlorosis event and have the ONLY green lawn on the block for the rest of the summer. Ironite will not touch our limestone soils. It's been tried many times. If you wait until the grass turns yellow to use the glauconite, you will have to wait the traditional 3 full weeks before you see the green return. Using greensand during the rain prevents the chlorosis altogether.

Greensand is damp and feels like sand. If you let it dry out it forms hard clumps. Thus it does not go through a spreader very well. I scatter it like I'm feeding chickens.

Oh and you went to the wrong place to get your soil test. As you already know, TAMU is very NPK oriented. If you wanted answers with respect to an organic program, they are absolutely the last place on earth to go. If you want more testing, better testing, more answers, better answers, and real customer services, next time go to the Texas Plant and Soil Lab. For $35 their regular test and results will knock your socks off. TSPL does their testing based on calibrated plant uptake technology. While TAMU and every other land grant college/university tests soil using hydrochloric acid to dissolve everything in the soil, TPSL uses carbonic acid (also known as carbonated soda water available in every soft drink) because that is what the plants use. The plants release CO2 into the soil via their roots. When the CO2 hits moisture, dilute carbonic acid forms and dissolves the minerals in the soil. Thus there is a huge difference between what is "available" to the plants and what can be dissolved in hydrochloric acid. TPSL's tests are really calibrated to plant uptake. When they tell you something is in the soil, they mean that it is available to the plants right away. So chlorosis would show up in a TPSL test but not in a TAMU test.

    Bookmark   May 4, 2008 at 1:32PM
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tex_jas(8b - College Station, TX)

Hey DCHall, sorry about that. Profile should be updated now. I'm in College Station, so that's how I wound up at TAMU. Thanks for the TPSL link though... I'll definitely go that route next time. The native soil around here is a very heavy clay. For the most part that's beneath probably 2 - 6 inches of loam that they leveled out the lot with.

I actually did see a small amount of greensand at one of the local garden shops a few weeks ago. Not enough for me to do 40lb/1000sqft, but I'm sure they could order some for me. The neighbors probably already feel sorry for me... Seeing me out there week after week now with one of the poorer lawns on the street. I guess standing out in a rainstorm feeding imaginary chickens probably won't surprise them at this point. :)

So if I've combined everyone's advice together, is it safe to say that since I'm out there spreading peat now, I will get the benefit of adding OM, and most likely a little reduction in pH, but that if the College Station soil is heavy in limestone, it's only a temporary solution. And to further buffer it, an application of greensand would be beneficial, repeating after downpours if I want to avoid chlorosis. Do you re-apply around the 40/1000 rate? I don't recall how much it costs, but I have a little shy of 7000 sq ft. Could get pricey in our wet years!

Thank you for the reply!

    Bookmark   May 4, 2008 at 2:33PM
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lou_midlothian_tx(z8 DFW, Tx)

I'm with David on greensand. We both live on limestone rubbles so you can see that we are growing st augustine grass with no problem. I can get greensand pretty cheap at Lowe's in DFW area for $3.56 for 40lbs bags. They are hard to spread so I use lava sand to help break them up and make it easier to spread by hand.

Peat is pretty much worthless. Basically sterile for the most part. You should have gotten compost instead to help buffer high pH....

    Bookmark   May 4, 2008 at 2:39PM
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Safe to assume that's still a good idea?

Fire when ready. Peat moss sure isn't going to hurt anything and might very well help. Topdress no more than 1/3" (I tend to go 1/4" so I have some slack for the inevitable ponding of the stuff).

So I did get some food in there last week. Should I let that bake a few more weeks before making another round with your suggestions?

Slam it. It's not going to hurt at all, but you can certainly wait a bit if you wish. After slinging around that much peat moss, you're not going to want to have anything to do with the lawn for a bit.

But perhaps I'm jaded. Ten flats of annuals for a total of nearly 800 and if I never see another annual again it'll be too durned soon.

    Bookmark   May 4, 2008 at 4:37PM
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tex_jas(8b - College Station, TX)

Yeah, I'm only about halfway through and pretty beat. The lawn's gonna be on auto-pilot for a while after this. In raking it in, a lot of the dead mess is coming up. I know it's generally taboo to remove it, but I honestly think there's more out there than the natural cycle can handle right now, so I'm taking the opportunity to thin it out some. Certainly not removing it all, but getting enough out that it looks a little better and there is a better chance for water and whatever else I'm adding to actually get down to the soil level.

Anyway, it's slow going and using long-since forgotten muscles.

That's a LOT of annuals! I think 2 flats is the most I've ever braved doing at once.

Lou, I don't recall ever seeing greensand at Lowes down here. I'll look again, but I'm gonna be up in DFW next weekend and will load up a few applications worth if I can't find that much here.

    Bookmark   May 4, 2008 at 5:29PM
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lou_midlothian_tx(z8 DFW, Tx)

I'm not sure but it seems that it's limited to DFW area only. For sure, Lowe's in Mansfield and Waxahachie have them. You could call the ones closest to wherever you will be to make sure esp with the gas prices being high already... I never saw them at Lowe's in Houston whenever I visit my mother (I usually do major yard chores every few months there). Not only that, they are much more expensive elsewhere, 2-5 times the cost!

My brother graduated from TAMU. Dated a chick there. Good times....

    Bookmark   May 4, 2008 at 9:41PM
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dchall_san_antonio(8 San Antonio)

Lowe's is the best place to get greensand if they have it. They carry a brand of mulches, soils, compost, etc. which I believe is called Earth's Finest. It is bagged by Living Earth Technology Company (LETCO) out of Dallas. But if it doesn't sell at one Lowe's, they drop the line. I can't get greensand at the Lowe's in San Antonio.

    Bookmark   May 4, 2008 at 11:10PM
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gardenfanatic(MO zone5b)

Don't apply gypsum - it will raise the pH.

    Bookmark   May 21, 2008 at 1:19AM
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